Non-tuberculous Mycobacteria in TB-suspected patients: a clinical, epidemiological and genetic study

Abstract

Introduction: Non-tuberculous Mycobacteria (NTM) are opportunistic pathogens causing community and hospital infections, often misdiagnosed as M. tuberculosis; accurate, timely differentiation is essential due to differing treatment strategies.

Objectives: To genotype NTM from TB-suspected patients at a tertiary care hospital and correlate findings with clinical and epidemiological features.

Methodology: A prospective observational study (Aug 2018–Dec 2019) analysed 2,050 pulmonary and extrapulmonary specimens from TB-suspected patients. Specimens were processed conventionally, MTBC and NTM were differentiated via MPT64 antigen test, and 42 randomly selected NTM isolates were genotyped using line probe assay targeting the 23S rRNA gene.

Results: Of 2,050 specimens, 8.8% (180/2050) yielded mycobacterial growth. Non-tuberculous Mycobacteria were detected in 104 (5.1%) of the samples. Among these, 42.3% of patients were aged > 45 years, with a male predominance (62.5%). Nearly half of the cases (47.1%) presented clinically with pulmonary disease. Genotypic characterisation by line probe assay identified M. abscessus as the most frequent species, accounting for 35.6% of the isolates.

Conclusions: NTM is prevalent among TB-suspected patients, with pulmonary disease and rapid-growing M. abscessus predominating, emphasizing the need for accurate species identification to guide management and public health measures.